Oxidative metabolism is impaired by phosphate deficiency during fracture healing and is mechanistically related to BMP induced chondrocyte differentiation.

Prior studies of acute phosphate restriction during the endochondral phase of fracture healing showed delayed chondrocyte differentiation was mechanistically linked to decreased bone morphogenetic protein signaling. In the present study, transcriptomic analysis of fracture callus gene expression in three strains of mice was used to identify differentially expressed (FDR = q ≤ 0.05) genes in response to phosphate (Pi) restriction. Ontology and pathway analysis of these genes showed that independent of genetic background, a Pi-deficient diet downregulated (p = 3.16 × 10-23) genes associated with mitochondrial oxidative phosphorylation pathways as well as multiple other pathways of intermediate metabolism. Temporal clustering was used to identify co-regulation of these specific pathways. This analysis showed that specific Ox/Phos, tricarboxylic acid cycle, pyruvate dehydrogenase. Arginine, proline metabolism genes, and prolyl 4-hydroxylase were all co-regulated in response to dietary Pi restriction. The murine C3H10T½ mesenchymal stem cell line was used to assess the functional relationships between BMP2-induced chondrogenic differentiation, oxidative metabolism and extracellular matrix formation. BMP2-induced chondrogenic differentiation of C3H10T½ was carried out in culture media in the absence or presence of ascorbic acid, the necessary co-factor for proly hydroxylation, and in media with normal and 25 % phosphate levels. BMP2 treatment led to decreased proliferation, increased protein accumulation and increased collagen and aggrecan gene expression. Across all conditions, BMP2 increased total oxidative activity and ATP synthesis. Under all conditions, the presence of ascorbate further increased total protein accumulation, proly-hydroxylation and aggrecan gene expression, oxidative capacity and ATP production. Lower phosphate levels only diminished aggrecan gene expression with no other effects of metabolic activity being observed. These data suggest that dietary phosphate restriction controls endochondral growth in vivo indirectly through BMP signaling, which upregulates oxidative activity that is linked to overall protein production and collagen hydroxylation.

Oral Chemotherapeutic Ingestions Reported to a Poison Control Center Treated in a Health Care Facility.

BACKGROUND: The approach to cancer chemotherapy has changed in recent years, and there are several new oral chemotherapeutics that offer convenience to patients. These medications have toxicity, which may be particularly amplified in an overdose. STUDY DESIGN: This was a retrospective review of all oral chemotherapy overdoses reported to the California Poison Control System between January 2009 and December 2019. Inclusion criteria were all ingestions coded as "antineoplastic, monoclonal antibody, or thalidomide" that were evaluated at a health care facility. We evaluated outcomes per AAPCC criteria (stratified as death, major, moderate, mild, or no effect) as well as symptoms and interventions. RESULTS: There were 314 total cases reported; 169 single-substance ingestions (54%) and 145 cases with coingestant(s) (46%). One hundred eighty cases were female (57%) and 134 male (43%). Age ranges were as follows: ages 1-10 years old (87 cases); ages 11-19 years old (26 cases); 20-59 years old (103 cases); ages 60 and older (98 cases). The majority of cases were unintentional ingestions (199, 63%). The most common medication reported was methotrexate with 140 cases (45%), followed by anastrozole (32 cases) and azathioprine (25 cases). One hundred thirty-eight cases were admitted to the hospital for further care (ICU 63 cases; non-ICU 75 cases). Eighty-four of the methotrexate cases received the antidote leucovorin (60%). Five of the capecitabine ingestions received uridine (36%). Outcomes included 124 cases with no effect, 87 cases with minor effect, 73 case with moderate effect, 26 cases with major effect, and 4 deaths. CONCLUSION: Although methotrexate is the most common oral chemotherapeutic agent involved in overdoses reported to the California Poison Control System, there are many other oral chemotherapeutics from various drug classes, which can lead to toxicity. Although deaths are rare, further studies are needed to determine if particular drugs or drug classes warrant more scrutiny.

Serum proteomic assessment of the progression of fracture healing.

A targeted proteomic analysis of murine serum over a 35-day course of fracture healing was carried out to determine if serum proteomic changes could be used to monitor the biological progression of fracture healing. Transverse, closed femoral fractures where generated and stabilized with intramedullary fixation. A single stranded DNA aptamer-based multiplexed proteomic approach was used to assay 1,310 proteins. The transcriptomic profiles for genes matching the 1,310 proteins were obtained by microarray analysis of callus mRNA. Of the 1,310 proteins analyzed, 850 proteins showed significant differences among the time points (p-value <0.05). Ontology assessment associated these proteins with osteoblasts, monocyte/macrophage lineages, mesenchymal stem cell lines, hepatic tissues, and lymphocytes. Temporal clustering of these data identified proteins associated with inflammation, cartilage formation and bone remodeling stages of healing. VEGF, Wnt, and TGF-ßsignaling pathways were restricted to the period of cartilage formation. Comparison of the proteomic and transcriptomic profiles showed that 87.5% of proteins in serum had concordant expression to their mRNA expression in the callus, while 12.5% of the protein and mRNA expression patterns were discordant. The discordant proteins that were elevated in the serum but down regulated in callus mRNA expression were related to clotting functions, allograft rejection, and complement function. While proteins down regulated in the serum and elevated in callus mRNA were associated with osteoblast function, NF-ĸb, and activin signaling. These data show the serum proteome may be used to monitor the different biological stages of fracture healing and have translational potential in assessing human fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1153-1163, 2018.